The overall objective of this research is to elucidate the unique relationship of the central nervous system and the immune system as a "network" in humans with primary malignant tumors. Further definition of the cellular mechanisms associated with impaired host immunocompetence of brain tumor patients will be determined by characterizing quantitative and qualitative defects in subpopulations of immunoregulatory lymphocytes obtained from these patients. Specifically, the function of the inducer/helper T cells (OKT4+) obtained from lymphocyte preparations from patients will be determined in the pokeweed mitogen assay for the induction of immunoglobulin synthesis by bone marrow-derived cells (B cells). The production and expression of interleukin 2 (IL-2) by lymphocytes from patients with brain tumors will be assessed. Studies will be conducted to further elucidate the mechanism(s) responsible for previously demonstrated intrinsic anomalies of lymphocyte activation. These will include experiments to examine the cellular kinetics of lymphocyte activation and proliferation. The role of cAMP and cGMP will also be determined by quantitating these cyclic nucleotides before and during mitogen activation of lymphocytes from patients. Finally, experiments will be conducted to examine various normal and neoplastic neural extracts for immunoregulatory properties via in vitro induction of quantitative and/or qualitative alterations in lymphocyte function. In particular, the role of specifically elevated hormones and prostaglandins in these patients as affecting alterations in lymphocyte function will be determined. (IS)